Method of controlling dishwasher and dishwasher

ABSTRACT

A dishwasher and method of controlling a dishwasher are provided. In the dishwasher and the method, a heater in a sump begins to be driven when a measured fluid supply frequency measured before the supply of wash fluid into the sump is complete reaches a predefined value, and thus heats the wash fluid in the sump. Thus, it is possible to reduce the time taken to heat the wash fluid in the sump to a target temperature, thus reducing the operating time of the dishwasher.

This application claims priority to Korean Patent Application No.10-2007-0088507 filed in Korea on Aug. 31, 2007, the entirety of whichis incorporated herein by reference in its entirely.

BACKGROUND

1. Field

This relates to a method of controlling a dishwasher and a dishwasher,and more particularly, to a method of controlling a dishwasher and adishwasher in which a supply of wash fluid and operation of a heater canbe effectively controlled.

2. Background

Dishwashers are appliances that wash dirty dishes with clean wash fluidsprayed from nozzles at high pressure. In general, dishwashers include awashing tub and a sump disposed below the tub that contains wash fluid.The operation of dishwashers are largely classified into a washingoperation, a drain operation, a rinsing operation and a dryingoperation.

Dishwashers may use warm wash fluid in order to improve the performanceof dishwashing or rinsing during a washing or rinsing operation. Inorder to provide warm wash fluid, dishwashers may include a heaterprovided in the sump so as to heat the wash fluid stored therein.However, driving a heater after the supply of wash fluid and heating thewash fluid in the sump to a target temperature is time- andenergy-consuming.

In particular, it generally takes a considerable amount of time to heata considerable amount of wash fluid to a high temperature of, forexample 65° C., which causes the operating time of a dishwasher toincrease.

SUMMARY

A method of controlling a dishwasher and a dishwasher is provided inwhich the operating time of a dishwasher can be reduced and energyefficiency can be improved by reducing the time taken to heat wash waterin a sump to a target temperature.

A method of controlling a dishwasher as embodied and broadly describedherein may include supplying wash water into a sump until the flow rateof wash water measured by a flow rate detection device reaches a firstset value; and heating the wash water in the sump by driving a heater ifthe flow rate of wash water measured by a flow rate detection devicereaches a second set value, the second set value being less than thefirst set value.

A dishwasher as embodied and broadly described herein may include asump; a water supply device which supplies wash water into the sump; aheater which heats the wash water in the sump; and a control unit whichcontrols the heater to heat the wash water in the sump during the supplyof wash water into the sump.

In accordance with embodiments as broadly described herein, a heater ina sump is driven and thus heats wash water in the sump when a measuredflow rate reaches a second set value. Thus, it is possible to reduce thetime taken to heat the wash water in the sump to a target temperature,thus reducing operating time of a dishwasher. In addition, it ispossible to improve energy efficiency due to convection in the sump.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 illustrates a cross-sectional view of a dishwasher according toan exemplary embodiment as broadly described herein;

FIG. 2 illustrates a schematic diagram of an airbrake of the dishwashershown in FIG. 1;

FIG. 3 illustrates a block diagram of the dishwasher shown in FIG. 1;and

FIG. 4 illustrates a flowchart of a method of controlling a dishwasheraccording to an exemplary embodiment as broadly described herein.

DETAILED DESCRIPTION

Exemplary embodiments will hereinafter be described in detail withreference to the accompanying drawings.

Referring to FIG. 1, a dishwasher 100 as embodied and broadly describedherein includes a tub 110 for washing dishes, a door 111 disposed at thefront of the tub 110 to open/close the washing tub 110, a sump 120disposed in the middle of the bottom of the tub 110 to store wash fluid,a heater 115 disposed in the sump 120 to heat wash fluid in the sump120, and upper and lower racks 131 and 132 movably positioned in the tub110 to hold dishes.

The dishwasher 100 also includes a washing pump 121 which pumps washfluid out of the sump 120 at high pressure, a washing motor 122 disposedon one side of the washing pump 121 to drive the washing pump 121, aguide 126 which guides the flow of the wash fluid pumped by the washingpump 121, a lower nozzle 123 disposed above the sump 120 to spray washfluid up toward the lower rack 132, an upper nozzle 124 connected to theguide 126 disposed below the upper rack 131 to spray wash fluid uptoward the upper rack 131, a top nozzle 125 disposed at the ceiling ofthe tub 110 to spray wash fluid down to the upper rack 131, a drain pump141 disposed on one side of the sump 120 to discharge wash fluid fromthe sump 120, and a drain motor 142 which drives the drain pump 141.

Referring to FIG. 2, the dishwasher 100 also includes an airbrake 160attached on an external lateral surface of the tub 110 to guide washfluid supplied by an external source into the sump 120 and to controlthe flow rate of wash fluid supplied into the sump 120.

The airbrake 160 includes a supply hose connector 161 through which washfluid for washing dishes is supplied and a supply path 162 which isconnected to the supply hose connector 161 and is U-shaped. A flow ratedetector 150 is installed in the airbrake 160. The flow rate detector150 is connected to the fluid supply path 162. The flow rate detector150 is rotated by wash fluid supplied into the sump 120 and measures theflow rate of wash fluid supplied into the sump 120.

Referring to FIG. 2, the flow rate detector 150 includes an impeller 151a rotated by the energy of wash fluid supplied into the sump 120, and amagnet 151 b disposed on the outer circumferential surface of theimpeller 151 a.

FIG. 3 illustrates a block diagram of the dishwasher 100. Referring toFIG. 3, the dishwasher 100 includes the flow rate detector 150 whichmeasures the flow rate of wash fluid supplied by an external source, atemperature sensor 155 disposed in the sump 120 to measure thetemperature of wash fluid in the sump 120, a controller 170 thatconverts a measured flow rate provided by the flow rate detector 150into a supply frequency and controls the operation of the heater 115 inthe sump 120 according to the supply frequency, and a memory 175 whichstores a first set value indicating a supply frequency when the supplyof wash fluid into the sump 120 is complete and a second set valueindicating a reference supply frequency for determining when to initiatethe operation of the heater 115 in the sump 120. The controller 170controls the general operation of the dishwasher 100.

A flowmeter may be used as the flow rate detector 150. The flow ratedetector 150 is disposed in the airbrake 160, and is rotated by washfluid supplied into the sump 120, and thus measures the flow rate ofwash fluid supplied into the sump 120. The flow rate detector 150includes the impeller 151 a, which is rotated by the energy of washfluid supplied into the sump 120, and the magnet 151 b, which isdisposed on the outer circumferential surface of the impeller 151 a. Ahall sensor (not shown) is disposed near the flow rate detector 150. Thehall sensor senses a magnetic field generated by the magnet 151 b uponthe rotation of the impeller 151 a and generates a corresponding pulse.

Wash fluid supplied through the supply hose connector 161 of theairbrake 160 flows along the supply path 162 and drops, thereby rotatingthe impeller 151 a of the flow rate detector 150. Then, the hall sensorsenses a magnetic field generated by the magnet 151 b and generates acorresponding pulse. Thereafter, the pulse generated by the hall sensoris transmitted to the controller 170, and is then transmitted into asupply frequency corresponding to the flow rate of wash fluid measuredby the flow rate detector 150.

The controller 170 controls the opening and closing of the supply valve165 and the operation of the heater 115 based on the flow rate of washfluid measured by the flow rate detector 150.

The controller 170 may control the supply of wash fluid into the sump120 by supplying wash fluid into the sump 120 until a supply frequencycorresponding to the flow rate of wash fluid measured by the flow ratedetector 150 reaches the first set value present in the memory 175. Thatis, if the supply frequency corresponding to the flow rate of wash fluidmeasured by the flow rate detector 150 reaches the first set value, thecontroller 170 may close the supply valve 165.

The first set value indicates a supply frequency when the supply of washfluid into the sump 120 is complete. If the upper nozzle 124 and thelower nozzle 123 are alternately driven, the first set value may be setto about 460 Hz. Alternatively, if only the lower nozzle 123 is drivenbecause only a few dishes are loaded in the tub 110, the first set valuemay be set lower than 460 Hz.

In order to control the operation of the heater 115, the controller 170may compare a supply frequency corresponding to the flow rate of washfluid measured by the flow rate detector 150 with the second set valuepresent in the memory 175. Thereafter, if the supply frequencycorresponding to the flow rate of wash fluid measured by the flow ratedetector 150 reaches the second set value, the controller 170 may turnon the heater 115 in the sump 120 and may thus heat the wash fluid inthe sump 120.

The second set value indicates a reference supply frequency fordetermining when to initiate the operation of the heater 115 in the sump120. The second set value may be less than the first set value. Thesecond set value may be set based on the time when the heater 115 beginsto be immersed in wash fluid.

The heater 115 generally begins to be immersed in wash fluid when thesupply frequency corresponding to the flow rate of wash fluid measuredby the flow rate detector 150 reaches 150 Hz. Thus, the second set valuemay be set to 150-250 Hz. In order to prevent the heater 115 fromgenerating heat even when being in a standby state, the second set valuemay be set to 200 Hz or higher.

Typically, wash fluid is supplied into the sump 120, and then the heater115 is driven during the driving of the washing pump 121, therebyheating the wash fluid in the sump 120. On the other hand, in theexemplary embodiment of FIGS. 1 through 3, the heater 115 is drivenbefore the supply of wash fluid into the sump 120 is complete. Morespecifically, the heater 115 is driven and thus heats the wash fluid inthe sump 120 when the supply frequency corresponding to the flow rate ofwash fluid measured by the flow rate detector 150 reaches the second setvalue.

Therefore, according to this exemplary embodiment, it is possible toreduce the time taken to heat the wash fluid in the sump 120 to a targettemperature and thus to reduce the operating time of the dishwasher 100.In addition, it is possible to improve energy efficiency due toconvection in the sump 120.

The flow rate detector 150 is not restricted to a flowmeter. That is,various devices, other than a flowmeter, may be used as the flow ratedetector 150 as long as they can measure the flow rate of wash fluidsupplied into the sump 120.

For example, a pressure switch may be used as the flow rate detector150. In this case, the pressure switch may be disposed at the bottom ofthe sump 120 to measure pressure in the sump 120. Then, the measuredpressure may be transmitted to the controller 170, and the controller170 may convert the measured pressure into a supply frequency.

A method of controlling the dishwasher 100 according to an exemplaryembodiment as broadly described herein will hereinafter be described indetail, mainly focusing on the control of the supply of wash fluid andthe control of the operation of the heater 115.

FIG. 4 illustrates a flowchart of a method of controlling the dishwasher100 according to an exemplary embodiment as broadly described herein. Inthe exemplary embodiment of FIG. 4, a flowmeter is used as the flow ratedetector 150, the first set value is set to 450 Hz, and the second setvalue is set to 200 Hz.

When a request for operation of the dishwasher 100 is issued by a user,the controller 170 supplies wash fluid into the sump 120 by opening thesupply valve 165 (S110). Wash fluid supplied by an external source isinjected into the sump 120 via the airbrake 160.

Once the supply of wash fluid into the sump 120 begins, the flow ratedetector 150 in the airbrake 160 measures the flow rate of wash fluidsupplied into the sump 120 and thus determines a supply frequency basedon the result of the measurement (S120). More specifically, wash fluidinjected into the flow rate detector 150 through the supply path 162 ofthe airbrake 160 rotates the impeller 151 a, and the magnet 151 bgenerates a magnetic field upon the rotation of the impeller 151 a. Thehall sensor, which is disposed near the flow rate detector 150, detectsthe magnetic field generated by the magnet 151 b and generates acorresponding pulse. Thereafter, the pulse generated by the hall sensoris transmitted to the controller 170, and the controller 170 convertsthe pulse generated by the hall sensor into a supply frequency.

During the supply of wash fluid into the sump 120, the controller 170determines whether a supply frequency corresponding to a measured flowrate provided by the flow rate detector 150 reaches the second setvalue, i.e., 200 Hz, or the point at which the heater 115 is immersed(S130).

If the supply frequency corresponding to the measured flow rate reaches200 Hz, the controller 170 turns on the heater 115 in the sump 120 andthus heats the wash fluid in the sump 120 (S140). In short, in theexemplary embodiment of FIG. 4, the controller 170 drives the heater 115and thus heats the wash fluid in the sump 120 as fluid continues to besupplied to the sump 120, and before the supply of wash fluid into thesump 120 is complete.

During the heating of the wash fluid in the sump 120, the controller 170determines whether the supply frequency corresponding to the measuredflow rate reaches the first set value, i.e., 460 Hz (S150).

If the water supply frequency corresponding to the measured flow ratereaches 460 Hz, the controller 170 terminates the supply of wash fluidinto the sump 120 by closing the supply valve 165 (S160).

Once the supply of wash fluid into the sump 120 is complete, thecontroller 170 turns on the washing motor 122 and thus drives thewashing pump 121 so as to pump wash fluid out of the sump 120 at highpressure (S170). As a result, a washing operation is performed on dishesheld by the upper rack 131 and/or the lower rack 132.

During the washing operation, the controller 170 determines whether atemperature measured from the wash fluid in the sump 120 by thetemperature sensor 155 reaches a target temperature (S180). The targettemperature may be an optimum wash fluid temperature for use in awashing operation. The target temperature may be automatically setaccording to a washing program chosen by the user or may be set manuallyby the user.

If the measured wash fluid temperature reaches the target temperature,the controller 170 terminates the heating of the wash fluid in the sump120 by turning off the heater 115 in the sump 120 (S190). During thewashing operation, the controller 170 may alternately turn on and offthe heater 115 so as to maintain the wash fluid in the sump 120 at thetarget temperature.

Thereafter, the controller 170 performs a subsequent operation (S200).That is, the controller 170 may sequentially perform a rinsing operationfor rinsing dishes loaded in the tub 110 and a drying operation fordrying the dishes loaded in the tub 110, thereby completing theoperation of the dishwasher 100.

It has been described above how to control the supply of wash fluid andthe operation of the heater 115 during a washing operation. However,embodiments as broadly descried herein are not restricted to this. Thatis, the supply of wash fluid and the operation of the heater 115 may becontrolled in a similar manner during a rinsing operation.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” “certain embodiment,” “alternativeembodiment,” etc., means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment as broadly described herein. The appearancesof such phrases in various places in the specification are notnecessarily all referring to; the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, numerous variations andmodifications are possible in the component parts and/or arrangements ofthe subject combination arrangement within the scope of the disclosure,the drawings and the appended claims. In addition to variations andmodifications in the component parts and/or arrangements, alternativeuses will also be apparent to those skilled in the art.

1. A method of controlling a dishwasher, the method comprising:supplying wash fluid into a sump until a flow rate of the wash fluidmeasured by a flow rate detector reaches a first set value; and heatingthe wash fluid in the sump by operating a heater when the flow rate ofthe wash fluid measured by the flow rate detector reaches a second setvalue, the second set value being less than the first set value.
 2. Themethod of claim 1, wherein the heater is positioned at a bottom portionof the sump and the second set value is based on a point at which theheater begins to be immersed in wash fluid.
 3. The method of claim 1,wherein the first set value is between approximately 150 and 250 Hz. 4.The method of claim 1, wherein heating the wash fluid comprises heatingthe wash fluid in the sump until a fluid temperature in the sump reachesa target temperature.
 5. The method of claim 1, wherein the flow ratedetector comprises a flowmeter, and wherein supplying wash fluid into asump comprises measuring the flow rate of wash fluid supplied into thesump as the flow of wash fluid rotates the flowmeter.
 6. The method ofclaim 1, wherein the flow rate detector comprises a pressure switchprovided in the sump to measure a fluid pressure in the sump.
 7. Adishwasher, comprising: a sump; a supply device that supplies wash fluidto the sump; a heater that heats the wash fluid in the sump; and acontroller that controls the heater to heat the wash fluid in the sumpas wash fluid is supplied to the sump.
 8. The dishwasher of claim 7,further comprising a flow rate detector that measures a flow rate ofwash fluid supplied to the sump, wherein the controller determines whento operate the heater based on the measured flow rate provided by theflow rate detector.
 9. The dishwasher of claim 8, wherein the flow ratedetector comprises: an impeller that is rotated by incoming wash fluid;and a magnet that generates a magnetic field as the impeller rotates.10. The dishwasher of claim 9, wherein the controller converts a pulsethat corresponds to the magnetic field generated by the magnet, into asupply frequency that corresponds to the measured flow rate.
 11. Thedishwasher of claim 8, wherein the controller supplies wash fluid to thesump until the flow rate measured by the flow rate detector reaches afirst set value, and wherein the controller heats the wash fluid in thesump by operating a heater when the flow rate measured by the flow ratedetector reaches a second set value.
 12. The dishwasher of claim 11,wherein the second set value is less than the first set value.
 13. Thedishwasher of claim 11, wherein the second set value is based on a pointat which the heater begins to be immersed in wash fluid.
 14. Thedishwasher of claim 11, wherein the controller operates the heater for afirst set time, and terminates operation of the heater for a second settime after the first set time has elapsed when the flow rate measured bythe flow rate detector reaches the second set value.
 15. The dishwasherof claim 11, wherein the controller operates the heater when the flowrate detector determines that wash fluid is being supplied to the sump.16. The dishwasher of claim 7, wherein the controller measures an amountof time taken to supply wash fluid to the sump and operates the heaterwhen the measured amount of time exceeds a predefined amount.
 17. Amethod of controlling a dishwasher, the method comprising: supplyingwash fluid to a sump; measuring a flow rate of the wash fluid as it issupplied to the sump, and comparing the measured flow rate to a firstset value and a second set value; turning on a heater and heating thewas fluid collected in the sump when the measured flow rate is greaterthan or equal to the second set value; and continuing to supply washfluid to the sump while the heater heats the wash fluid collected in thesump until the measured flow rate is equal to the first set value. 18.The dishwasher of claim 17, wherein measuring a flow rate of the washfluid comprises: directing the wash fluid across an impeller to rotatethe impeller; generating a magnetic field using at least one, magnet inresponse to the rotation of the impeller; and generating a fluid supplyfrequency based on the magnetic field generated by the at least onemagnet that corresponds to a flow rate of the wash fluid being suppliedto the sump.
 19. The dishwasher of claim 18, wherein turning on a heaterand heating the wash fluid collected in the sump when the measured flowrate is greater than or equal to the second set value comprises turningon the heater when the fluid supply frequency is greater than or equalto the second set value, wherein a fluid supply frequency of the secondset value corresponds to a point at which the heater is immersed in thewash fluid collected in the sump.
 20. The dishwasher of claim 19,wherein continuing to supply wash fluid to the sump while the heaterheats the wash fluid collected in the sump until the measured flow rateis equal to the first set value comprises supplying wash fluid to thesump until the fluid supply frequency is equal to the first set value,wherein a fluid supply frequency of the first set value corresponds to apoint at which the sump is at a predefined fill level required for aselected operation of the dishwasher.
 21. The dishwasher of claim 20,further comprising continuing to heat the wash fluid collected in thesump until a temperature thereof is greater than or equal to a targettemperature, and then shutting off the heater.
 22. The dishwasher ofclaim 21, further comprising intermittently turning the heater on andoff to maintain the wash fluid collected in the sump at the targettemperature.